fatal error LNK1127: library is corrupt --> after adding extern "C" to function prototype

I have an external library made using C code. I wish to call a function from the library in my c++ project. The original format of the function prototype was.

extern void butterThreeBp(real_T eml_dt, real_T eml_fl, real_T eml_fu, real_T eml_b3[7], real_T eml_a3[7]);

And this caused the following linker error in MSVC2008

error LNK2019: unresolved external symbol "void __cdecl butterThreeBp(double,double,double,double * const,double * const)" (?butterThreeBp@@YAXNNNQAN0@Z) referenc开发者_JAVA百科ed in function "public: void __thiscall myThread::setDRNLc(double)" (?setDRNLc@myThread@@QAEXN@Z)

I then changed this prototype to

extern "C" void ...

and then get the following error:

\butterThreeBp.lib : fatal error LNK1127: library is corrupt

I have rebuilt the library numerous times and am pretty certain that it is not corrupt. Any help would be great. Thanks!!

You do not have to use the included LCC compiler with MATLAB. The simplest solution is to get MATLAB to use VC++. http://www.mathworks.com/support/compilers/R2010b/index.html

IIRC you should add extern "C" only when compiling with C++ compiler.

Something like that:

#ifdef __cplusplus
extern "C" {
#endif

// the declarations

#ifdef __cplusplus
}
#endif  

Got it! I generated the library code using the MATLAB embedded coder and was using Matlab's Lcc built in compiler to build the library. I am working on the main application in MSVC, therefore I guess there must have been some calling convention problem between the library (Lcc) and my main project (MSVC). This problem was particularly difficult to spot because one of my libraries (ButterOneLp) worked fine, even though it was generated using Lcc. However, another library did not work.

The problem was fixed by using the

mex -setup

. . . command in MATLAB and changing the default compiler to MSVC as opposed to the default Lcc.

I think that Lcc is based on gcc, so if anybody knows how to change the calling convention in the C++ code so that gcc/lcc libraries can be called from MSVC, that would be great. However, that is a whole different question to the original on posted.

The moral of this story is to check that your library and calling application are/were built using the same compiler if you get a "fatal error LNK1127: library is corrupt".